There are several tools known in the art for crimping a prosthetic device such as a stent or a prosthetic heart valve or the like to a small diameter so that the prosthetic device can be introduced into a human or animal body minimally invasive via a catheter.
U.S. Pat. No. 5,911,752 discloses to collapse a stent by deforming a portion of the stent beyond the elastic limit. The stent is pushed through a frustoconical body which causes collapsing of the stent thus reducing its outer diameter.
WO 2010/096176 A1 discloses a crimping tool for a collapsible prosthetic device such as a prosthetic heart valve, said tool having a plurality of resilient tines defining an array around a longitudinal axis of the crimping tool. The plurality of tines is adapted to intersect a plurality of openings in the prosthetic device in an assembled position of the crimping tool on the prosthetic device to prevent pinching of the prosthetic device structure by its stent frame as the prosthetic device is collapsed. Subsequently, the prosthetic device with the tines is pushed through a frustoconical body for collapsing the prosthetic device.
WO 2007/120543 discloses a crimping tool having a first reducing member comprising a first tapered surface and a second reducing member comprising a second tapered surface. The prosthetic device is collapsed by moving the prosthetic device along a tapered surface of the first member and drawn into a sheath of a catheter.
It is an object of the invention to provide a crimping tool with improved handling and which allows for a gentle processing of a collapsible prosthetic device.
Another object is to provide a method for a method for crimping a prosthetic device with a crimping tool.
The objects are achieved by the features of the independent claims. The other claims, the description and the drawings provide advantageous developments of the invention.
In a first aspect of the invention a crimping tool for reducing an external dimension of a compressible prosthetic device is proposed, said crimp tool comprising                a first member having a longitudinal axis and comprising a first control surface, said first control surface being collapsible between a first state and a second state, said first member having a first open end and a second open end, the first open end being configured for introducing the prosthetic device when the first control surface is in said first state, and said second open end being configured for allowing locking of the prosthetic device, when introduced into the first member, to the first member;        an engagement portion for causing the first control surface to at least move from the first state to the second state when interacting with the first member; and        an actuator portion for moving the first member along the longitudinal axis for allowing the engagement portion to interact with the first member.        
It is of advantage that the prosthetic device can easily be locked to the first member when it protrudes from the second open end of the first member, e.g. by usage of a splint or the like. As a result, the inserted prosthetic device moves with the first member when the first member is moved, e.g. pulled through the engagement portion along the longitudinal axis. When the prosthetic device comes into contact with the first control surface, the collapsible prosthetic device can collapse in conjunction with the first control surface. As it is the outer surface of the first member which experiences a sliding movement relative to the engagement portion, the outer surface of the prosthetic device is protected from damage caused by sliding movements.
Advantageously, the crimping tool is easy to handle even in a saline bath in a sterile environment of an operating theatre which is required for handling of e.g. a prosthetic heart valve or the like. The overall dimensions of the crimping tool are reasonable so that an overlarge saline bath is not necessary. There are only few parts and steps necessary for collapsing the prosthetic device. Manipulating the crimping tool is easy to teach and to learn. Handling of the crimping tool is intuitive and systematic. The crimping tool is low weight and economically priced. Because there are not so many parts necessary, the danger of an individual part being dropped on the floor is reduced.
In an advantageous embodiment, the first member may be slidably arranged in a second member having a first open end and an opposing second open end. The second member allows for a stable arrangement and secure movement of the first member, thus allowing for a controlled collapsing of the prosthetic device.
In an advantageous embodiment, the second end may comprise the engagement portion, said engagement portion having an opening for allowing a sliding movement of the first member along the longitudinal axis. The arrangement is particularly compact and stable. In particular, the engagement portion may be a ring being arranged at the second end of the second member. When the prosthetic device is arranged in the first member, the prosthetic device collapses when the first member collapses.
In an advantageous embodiment, the first member may be configured as a collet having a receiving sleeve comprising a multitude of shell portions separated by cuts predominantly parallel to the longitudinal axis, said multitude of shell portions forming a splayed shell in the first state of the first member, said multitude of shell portions being attached to a ring.
For instance, the first member can be imagined as a piece of bamboo split with a knife into several, e.g. six, pieces on one end. These several pieces are splayed out to create a cone shape. The prosthetic device may be inserted into this cone, when the cone is collapsed to its original shape the prosthesis is crimped.
In an advantageous embodiment, the second member may be a cage structure configured to enclose the first member when said first member is in said first state. This allows for a low weight and stable arrangement.
In an advantageous embodiment, a third member is provided which is releasably connectable to the first end of the first member. The third member may provide additional and mild support for the prosthetic device when introduced into the first member. The third member may be in form of a cap which closes the first open end of the first member.
In an advantageous embodiment, the third member may comprise a screw thread for connecting to the first member. Thus, the third member can be easily connected, i.e. screwed, to the first member, while the prosthetic device is pushed into the first member. In alternative embodiments, a connection between the third member can be established via a bayonet lock, a friction lock or the like.
In an advantageous embodiment, the third member may have a receptacle for a portion of the prosthetic device. The prosthetic device can be arranged with one end in the third member and with an opposite end be pushed into the first member while the third member is attached to the first member.
In an advantageous embodiment, the receptacle may be an annular collar arranged on the third member. This allows for a simple mounting of the prosthetic device.
In another aspect of the invention a method for crimping a prosthetic device with a crimp tool is proposed by performing the steps                providing a first member having a longitudinal axis and comprising a first control surface, said first control surface being collapsible between a first state and a second state, said first member having a first open end and a second open end, the first open end being configured for introducing the prosthetic device when the first control surface is in said first state, and said second open end being configured for allowing locking of the prosthetic device, when introduced into the first member, to the first member;        providing an engagement portion for causing the first control surface to at least move from the first state to the second state when interacting with the first member;        providing an actuator portion for moving the first member along the longitudinal axis for allowing the engagement portion to interact with the first member; and        collapsing the first control surface from the first state to the second state by passing the first member through the engagement portion in direction of the longitudinal axis.        
Advantageously, the method is a gentle of crimping with reduced trauma to external stitches of the prosthetic device, e.g. a prosthetic heart valve or the like.
Particularly, the prosthetic device may be pushed and locked into a first member such as a cone until capture tangs of the prosthetic device protrude. The tangs may be locked onto a catheter. Then a collet may be moved forward by holding the hooks in place and pulling the lock ring forward. This action collapses the conical first body to a cylinder and crimps the prosthetic device. The prosthetic device can now be loaded to a loading area of a catheter.
In an advantageous embodiment, a second member may be provided including the engagement portion for interacting with the first member, thus facilitating the movement of the first member.
In an advantageous embodiment, a third member may be provided for introducing the prosthetic device into the first member. The third member can be utilized for pushing the prosthetic device into the first member.
The present invention together with the above-mentioned and other objects and advantages may best be understood from the following detailed description of the embodiments, but not restricted to the embodiments, wherein is shown in: